Switch of the reversing-type

ABSTRACT

The switch includes a base or block mounting first and second pairs of fixed contacts, with each of these contacts having a portion thereof adjacent the wall of a bore formed in the base centrally thereof. A cylinder is rotatably received in this bore, the cylinder carrying first and second movable contacts. An actuating arm is provided to move the cylinder back and forth between a first position wherein the first and second movable contacts respectively connect the contacts of the first and second pairs of fixed contacts with each other and a second position wherein the first and second movable contacts respectively connect different ones of the first pair of contacts with the contacts of the second pair of contacts.

United States Patent Braun [451 Jan. 25, 1972 [54] SWITCH OF THE REVERSING.TYPE 2,197,692 4/1940 Gill ..200/8 R 3,467,801 9/1969 Matthews ..200/157 [72] Inventor: Hermann E. Braun, Chicago, ill. [73] Assignee: Skil Corporation, Chicago, 111. FOREIGN PATENTS OR APPLICATIONS Filed: J 26,1970 484,697 10/1917 France ..20()/1 RV [21] Appl..No.: 56,074 Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Related US. Application Dat Armrney-McDougall, Hersh and Scott [63] Continuation of Ser. No. 748,271, July 29, 1968, ABSTRACT abandoned.

The switch includes a base or block mounting first and second 2] [1 C Z /1 ,200/1 V, ZO /ll A, pairs of fixed contacts, with each of these contacts having a 200/157 portion thereof adjacent the wall of a bore formed in the base IL 1- Jlolh H0111 /1 H0111 2 2 centrally thereof. A cylinder is rotatably received in this bore, Field of Search 155 11 11 A. the cylinder carrying first and second movable contacts. An 200/1 V, 8 R, 166 166 B6 actuating arm is provided to move the cylinder back and forth between a first position wherein the first and second movable 1 References Cilfid contacts respectively connect the contacts of the first and second pairs of fixed contacts with each other and a second UNITED STATES PATENTS position wherein the first and second movable contacts 2,921,147 H1960 Hun R X respectively connect different ones of the first pair of contacts 3,258,547 6/1966 Rector zoo A with the contacts of the second pair ofcontacts. 1,556,828 10/1925 Wvman ..200/1 RV '14 Claims, 8 Drawing Figures PATENTEU JAHZS ISYZ SHEET 10F 2 INVENTOR HER/MANN E. B AUN' sbzvwwz ATT'YS.

PATENTEDJANZSIHYZ 3.657367 sum 2 or 2 IO?- 27 I9 IO )6 I4 50 ljQa. in lg r u 5 '1 I J IN VEN TOR ATT' Y5.

H MANN E. BRAUN h- SWITCH OF THE REVERSING-TYPE RELATED APPLICATIONS This is a continuation of application Ser. No. 748,271 filed July 29, 1968, and now abandoned.

OBJECTS OF THE INVENTION A primary object of the present invention is the provision of a new and improved switch having first and second pairs of fixed contacts and first and second movable contacts selectively permitting connection of the contacts of the first and second pairs of fixed contacts with each other and, alternately, connection of different ones of the contacts of the first pair of contacts with the contacts of the second pair of contacts.

Another object of the present invention is the provision of a new and improved switch of the type described for use with an electric motor for reversing the direction of rotation thereof.

Still another object of the present invention is the provision of a new and improved switch of the type described, wherein such switch includes six contact strips defined by three pairs of contact strips, the contacts of each pair of contacts being identical.

Another object of the present invention is the provision of a new and improved switch of the type described which may be readily and inexpensively constructed from a very minimum of parts.

Still another object of the present invention is the provision of a new and improved switch of the type under consideration, wherein such switch is readily adapted for mounting on the body of a trigger-actuated switch, the latter being of the type adapted for mounting within the housing of a portable electric tool.

Another object of the present invention is the provision of a new and improved switch of the type under consideration, wherein such switch includes fixed contact strips, each having an end portion bent to define a push-in terminal.

These and other objects and advantages of the invention will become apparent from the following specification disclosing a preferred embodiment shown in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of one embodiment of the switch according to the present invention showing the same operatively associated with a trigger actuated switch, the latter being of the type for mounting within the housing of a portable electric tool;

FIG. 2 is an enlarged, exploded perspective view showing the switch of the present invention;

FIG. 3 is an enlarged, partial elevation and partial vertical section of the rotatable element of the switch;

FIG. 4 is a top plan view of the element shown in FIG. 3;

FIG. 5 is a bottom plan view of the element shown in FIG. 3;

FIG. 6 is a top plan view showing only the fixed contacts and the block mounting the same;

FIG. 7 is a section taken along line 7 -7 of FIG. 6; and

FIG. 8 is an electrical schematic illustrating exemplary current paths brought about by operation of the switch.

DESCRIPTION OF A PREFERRED EMBODIMENT The switch according to the present invention has a base structure including a block I0 of dielectric material with end walls 11, sidewalls I2 and upper and lower faces 14 and I5, respectively. The block 10 includes a central through bore 16. Formed in the block 10 and opening into the face 14 thereof is a pair of cavities I8 and 19. The cavity 18 has a narrow throat portion 18a which opens into the bore 16; this cavity has a wider throat portion 18b which opens to one of the sidewalls 12 of the block. It will be understood the cavity 19 is identical with the cavity 18 and arranged in the offset, opposite hand relation thereto as indicated in FIGS. 2 and 6.

Formed in the block 10 is a small slot 20 having a depth the same as that of the cavity 18; this slot opens at the face I4 of the block and also opens into the bore 16. The block 10 includes a similar slot 21 having a depth the same as that of the cavity 18. This last-mentioned slot opens at the face 14 of the block and also opens into the bore 16. Actually, the slots 20, 21 may be considered as portions of the cavities l8, 19 as the former are connected with the latter by arcuate cutouts 18c, 190, respectively, formed in the'wall of the bore 16. It will be understood the cutout 180 extends for the full depth or thickness of the block 10.

The block 10 is further defined by cavities 22, 23 and slots 24, 25 (FIGS. 6 and 7) which open at the face 15 of the block. These cavities and slots are identical with the respective cavities l8, l9 and slots 20, 21 and are arranged in the block such that they would appear exactly as shown in FIG. 2 were the block 10 to be turned over about its transverse centerline.

A first pair of contact strips 27, 28, identical with each other, are respectively received in the cavities 19 and 23. Referring to FIG. 6, it will be noted the contact strip 27 has an arcuate portion 27a received within the cutout I with the inner surface of the former being in smooth uninterrupted relation with the surface of the bore 16. One end 27b of the contact strip is received within the slot 21 thereby to aid in properly positioning the arcuate portion 27a. The other end 270 of the contact strip is bent to form a U-shaped formation, this end of the strip acting to define a so-called push-in terminal. It will be understood the contact strip 28 is mounted within the cavity 23 in precisely the same manner as just described with respect to the mounting of contact strip 27 in the cavity 19.

The block 10 mounts anotherpair of contact strips 30, 31, these strips being identical with-each other. The contact strip 30 is received within the cavity 18, with one end tab 300 of this contact strip being received within the slot 20 thereby to aid in mounting an arcuate portion 30b of the contact strip within the cutout with the inner surface of the former in smooth uninterrupted relation with the wall of the bore 16 as clearly seen in FIG. 6. The strip portion 30b extends for substantially the full height or depth of the block 10. The other end 306 of the contact strip is bent to form a U-shaped formation, this end of the strip acting to define a push-in terminal. It will be understood the contact strip 31 is received within the cavity 22 in the same manner as just described with respect to mounting of the contact strip 30 in the cavity 18.

A cylinder 34 of dielectric material is rotatably received within the bore 16. Adjacent one end of the cylinder 34 is a cutout formation 35 receiving a contact strip 36 in a manner for carrying the latter for rotation with the cylinder 34. The strip 36 has end portions 36a, 36!) which are sprung in such a manner as to be urged in yieldable engagement with the bore 16 and portions of the contact strips as will be explained hereinbelow. The member 34 includes at the other or lower end thereof another cutout formation 37 identical with the formation 35 but rotated 90 with respect thereto. This cutout portion receives a contact strip 38, the latter being identical with the contact strip 36. Thecontact strip 38 includes end portions 38a and 38b.

The cylinder 34 is illustrated in FIG. 2 in a neutral position in which it occupies only when passing back and forth between two positions to be explained below. In one position of the cylinder 34 the same is rotated in a counterclockwise position approximately 45 from the position shown in FIG. 2 such that the contact end 36a is in engagement with the contact strip portion 27a and the contact end 36b is in engagement with the contact strip portion 30b. When the cylinder 34 is in the same position, the contact end 380 is in engagement with the contact strip portion 28a and the contact end 38b is in engagement with the contact strip portion 31b. At this time it should be mentioned that the contact end 36a always remains in engagement with the contact strip portion 27a and that the contact strip portion 28a is alternately engaged by contact ends 38a, 38b.

The cylinder 34 is moved to its other position by rotating the same in a clockwise direction for approximately 45 from the position shown in H0. 2. When the cylinder 34 is swung to this position, the contact end 36b will separate from the contact end 30b and come into engagement with the contact strip portion 31b. When the cylinder 34 is rotated to this position, the contact end 38a separates from the contact strip portion 28a and comes into engagement with the contact strip portion 30b simultaneously with departure of the contact end 38b from the contact strip portion 31b and engagement of the contact end 38b with the contact strip portion 28a.

The base of the switch is further defined by the upper and lower plates 40, 41, respectively, formed of suitable dielectric material and secured to respective faces 14 and of the block in substantial coextensive contact therewith. These plates may be secured to the block by fasteners in the form of small bolts 43, 44 and associated nuts 45, 46. Of course, rivets or other suitable fasteners may be used in lieu of the bolts and nuts just mentioned. The bolts 43, 44 are received in openings 40a in the plate 40 and bores 10a, 10b in the block 10 and in openings 41a in the plate 41. The plates 40 and 41 include respective circular openings 47, 48, which openings are in alignment with each other and receive respective pinlike members 49, 50 extending integrally from the cylinder member 34 centrally of the latter thereby rotatably mounting the cylinder 34 for movement back and forth between the positions just described. The cylinder 34 includes an integral, upstanding formation 52 freely received within an arcuate slot 53 formed within the upper plate 40. The formation 52 is received within a notch 55a formed in one end of an actuating arm 55. The actuating arm may be pivotally mounted intermediate its ends about the bolt 44, the latter being slightly longer than the bolt 43 for this purpose. The arm 55 has an enlarged end 55b which covers the slot 53 regardless of the position of the am; this feature prevents entry of foreign particles into the switch interior.

The cylinder 34 is detented or yieldably held in each of the two positions just mentioned by means of a ball 57 received in a blind bore 58 formed in the cylinder 34 as best seen in HQ 3. A coil spring 59 contained within this blind bore engages the ball 57 urging the latter upwardly and allowing the same alternately to be partially received within the small bores 60, 61 formed in the upper plate 40.

As noted in FIG. 1, the switch according to the present invention may be readily mounted on a trigger actuated switch, generally designated 63, which switch may be of the type shown in Matthews et al. US. Pat. Nos. Re. 26,267 and 3,389,365. Such trigger actuated switch includes a body 64 movably mounting a trigger 65. This trigger actuated switch, which is adapted for mounting within the housing of a portable electric tool, may include contacts for simply energizing the tool motor, or such switch may include a speed control system of the type shown in Gawron US. Pat. No. 3,209,228 for providing variable speed of the tool motor. In a preferred form of the present invention, the actuating arm 55 has an end 55c disposed in overlying adjacent relation with the trigger 65 for actuation of the member 55 by the operators trigger finger.

In FIG. 8, the reversible electric motor of the tool is indicated at 67, the lines from a suitable source of alternating current being indicated at 68 and 69. It should be apparent that when the arm 55 is swung to one side to locate the cylinder 34 in one of the positions illustrated, the contacts 36, 38 will be in the solid line position illustrated in FIG. 8 for energizing the motor 67 in one direction. When the arm 55 is swung to the other side of the trigger 65, the cylinder 34 will be moved to its other position thereby locating the contacts 36 and 38 in the broken line positions illustrated in FIG. 8 for energizing the motor in its other direction. Actuation of the tool trigger will energize or operate the motor in the direction of rotation governed by the position of the arm 55.

It should be apparent the present invention provides a new and improved switch of the reversing type. It will be understood that the switch of the present invention is not to be limited for use with the trigger actuated switch as illustrated in FIG. I, as the switch according to the present invention obviously has many other uses. The switch according to the present invention may be inexpensively constructed as it contains a minimum of parts, with many of the parts being mere duplicates of each other. Because of the simplicity of construction, the switch may be made quite small and compact.

I claim:

1. A switch comprising a base mounting first and second pairs of fixed contacts, a member rotatably mounted by said base and carrying first and second movable contacts each having a pair of contacting ends, the movable contacts being arranged relative to each other such that each of said contacting ends is in a nonconducting relationship with adjacent contacting ends, means for rotating said member back and forth between a first position wherein said first and second movable contacts respectively connect one contact of the first pair of contacts with one contact of the second pair of contacts and the other contact of the first pair of contacts with the other contact of the second pair of contacts and a second position wherein said first and second movable contacts respectively connect said one contact of the first pair of contacts with said other contact of the second pair of contacts and said other contact of the first pair of contacts with said one contact of the second pair of contacts, said one contact of the first pair of contacts having an arcuate extent such that one contacting end of said first movable contact is in engagement therewith in both of said positions, said other contact of the first pair of contacts having an arcuate extent such that it is engaged by one contacting end of said second movable contact when said member is in said first position and by the other contacting end of said second movable contact when said member is in said second position.

2. The switch according to claim I further defined by, said base including a block having a bore, said base having a plurality of cavities each opening into said bore and respectively mounting said fixed contacts with each of the fixed contacts having a portion thereof adjacent the wall of said bore, said member consisting of a cylinder rotatably received in said bore, each of said movable contacts having pairs of end portions engageable respectively with said portions of the associated fixed contacts upon rotation of said cylinder back and forth between said first and second positions.

3. The switch according to claim 2 further defined by, each of said fixed contacts being generally in the form of a strip, said strips having respective ends thereof defining said fixed contact portions, said strips each having opposite ends shaped to define push-in terminals.

4. A switch comprising a base mounting first and second pairs of fixed contacts, a member rotatably mounted by said base and carrying first and second movable contacts, means for rotating said member to a first position wherein said first and second movable contacts respectively connect one contact of the first pair of contacts with one contact of the second pair of contacts and the other contact of the first pair of contacts with the other contact of the second pair of contacts and to a second position wherein said first and second movable contacts respectively connect said one contact of the first pair of contacts with Said other contact of the second pair of contacts and said other contact of the first pair of contacts with said one contact of the second pair of contacts, said base including a block having a bore, said base having a plurality of cavities each opening into said bore and respectively mounting said fixed contacts with each of the fixed contacts having a portion thereof adjacent the wall of said bore, said member consisting of a cylinder rotatably received in said bore, each of said movable contacts having a pair of end portions engageable respectively with said portions of the associated fixed contacts upon rotation of said cylinder back and forth between said first and second positions, said cavities being four in number with two of the cavities opening at sides of the block and at one face thereof and with the other two of said cavities opening at sides of the block and atthe opposite face of the latter, a pair of plates secured to said block in substantial coextensive contact with said one and said opposite face thereof, respectively, and thereby cooperating with said cavities to define substantially closed spaces containing said fixed contact strips.

5. The switch according to claim 4 further defined by, each of said fixed contacts being in the form of a spring strip having an end adjacent the portion of the associated cavity which opens at a side of the block, and end of each strip being bent to define a push-in terminal.

6. The switch according to claim 4 further defined by, said plates each having an opening in coaxial relation with the opening in the other plate, which openings respectively receive opposite end portions of said cylinder thereby rotatably mounting the latter.

7. The switch according to claim 2 further defined by, said cylinder having a cutout portion adjacent one end thereof receiving said first movable contact with opposite ends of the latter disposed adjacent the outer surface of the cylinder, said cylinder having another cutout portion at its other end receiving said second movable contact with opposite ends of the latter disposed adjacent the outer surface of the cylinder.

8. The switch according to claim 7 wherein said first movable contact is identical with said second movable contact, and wherein the contacts defining each of said first and second pairs of fixed contacts are identical with each other.

9. The switch according to claim 1 in combination with a trigger actuated switch, the latter being of the type adapted for mounting in a portable tool and including a body movably mounting a trigger, said base being fixedly mounted on said body, a manual actuating arm connected with said member for rotating the same back and forth between its first and second positions.

10. The combination according to claim 9 further defined by, said arm being pivotally mounted on said base intermediate the ends of the former, one end of the arm being engaged with said member and the other end of the arm being disposed in the vicinity of said trigger.

11. A switch comprising:

a. base means mounting first and second pairs of fixed contacts, which base means define a bore interiorly thereof, which bore exposes portions of each of said fixed contacts;

b. a member received in said bore for rotation about the longitudinal central axis thereof;

c. said member having integral coaxial formations journaled by said base means thereby supporting said member for rotation about said axis, said member having another integral formation eccentric with respect to said axis;

d. said base means having an opening receiving said another formation and permitting movement thereof in said opening during corresponding movement of said member back and forth between first and second positions;

e. a portion of said another formation extending through said opening and being disposed exteriorly of said base means;

. an actuating arm pivotally mounted by said base means, which arm has a recess receiving said another formation whereby actuation of said arm serves to move said member back and forth between said positions thereof; and

g. a third pair of contacts mounted by said member for operative engagement with said first and second pairs of fixed contacts for establishing a current path when said member is in said first position and for establishing a different current path when said member is in said second position.

12. The switch according to claim 11 further defined by said member having a pair of cutout formations receiving said third pair of contacts, respectively, said third contacts being in the form of strips contained in planes parallel with said axis of rotation.

13. The switch according to claim 11 further defined by said base means having a plurality of cavities each opening into said bore and respectively receiving portions of said fixed contacts, said portions of said fixed contacts being shaped to define push-in terminals.

14. A switch comprising:

a. base means including block means defining a central bore, a first pair of cavities adjacent one end of the bore and communicating therewith and a second pair of cavities adjacent the other end of the bore and communicating therewith;

b. a member mounted for rotation about the longitudinal central axis of said bore;

c. first and second pairs of contact strips mounted respectively in said first and second pairs of cavities by engagement with walls of the latter, with a portion of each of said strips extending into said bore and thereby defining a contact making surface extending longitudinally of the bore;

. said base means including plate means covering said first and second pairs of cavities thereby capturing and substantially enclosing said first and second pairs of contact strips therein;

. a third pair of contact strips carried by said member and each having a pair of contact making surfaces extending longitudinally of said bore adjacent the outer surface of said member, said surfaces of the third pair of contact strips being arranged for operative engagement with said contact making surfaces of said first and second pairs of contact strips for establishing a current path when said member is in said first position and for establishing a different current path when said member is in another position; and

f. the contact making surfaces of two-of said contact strips extending longitudinally of said bore to an extent such that electrical communication is established between one contact strip of said first pair of contact strips and one contact strip of said second pair of contact strips simultaneously with establishment of electrical communication between the other contact strip of said first pair of contact strips and the other contact strip of the second pair of contact strips when said member occupies one of its aforesaid positions for establishing one of said current paths. 

1. A switch comprising a base mounting first and second pairs of fixed contacts, a member rotatably mounted by said base and carrying first and second movable contacts each having a pair of contacting ends, the movable contacts being arranged relative to each other such that each of said contacting ends is in a nonconducting relationship with adjacent contacting ends, means for rotating said member back and forth between a first position wherein said first and second movable contacts respectively connect one contact of the first pair of contacts with one contact of the second pair of contacts and the other contact of the first pair of contacts with the other contact of the second pair of contacts and a second position wherein said first and second movable contacts respectively connect said one contact of the first pair of contacts with said other contact of the second pair of contacts and said other contact of the first pair of contacts with said one contact of the second pair of contacts, said one contact of the first pair of contacts having an arcuate extent such that one contacting end of said first movable contact is in engagement therewith in both of said positions, said other contact of the first pair of contacts having an arcuate extent such that it is engaged by one contacting end of said second movable contact when said member is in said first position and by the other contacting end of said second movable contact when said member is in said second pOsition.
 2. The switch according to claim 1 further defined by, said base including a block having a bore, said base having a plurality of cavities each opening into said bore and respectively mounting said fixed contacts with each of the fixed contacts having a portion thereof adjacent the wall of said bore, said member consisting of a cylinder rotatably received in said bore, each of said movable contacts having pairs of end portions engageable respectively with said portions of the associated fixed contacts upon rotation of said cylinder back and forth between said first and second positions.
 3. The switch according to claim 2 further defined by, each of said fixed contacts being generally in the form of a strip, said strips having respective ends thereof defining said fixed contact portions, said strips each having opposite ends shaped to define push-in terminals.
 4. A switch comprising a base mounting first and second pairs of fixed contacts, a member rotatably mounted by said base and carrying first and second movable contacts, means for rotating said member to a first position wherein said first and second movable contacts respectively connect one contact of the first pair of contacts with one contact of the second pair of contacts and the other contact of the first pair of contacts with the other contact of the second pair of contacts and to a second position wherein said first and second movable contacts respectively connect said one contact of the first pair of contacts with said other contact of the second pair of contacts and said other contact of the first pair of contacts with said one contact of the second pair of contacts, said base including a block having a bore, said base having a plurality of cavities each opening into said bore and respectively mounting said fixed contacts with each of the fixed contacts having a portion thereof adjacent the wall of said bore, said member consisting of a cylinder rotatably received in said bore, each of said movable contacts having a pair of end portions engageable respectively with said portions of the associated fixed contacts upon rotation of said cylinder back and forth between said first and second positions, said cavities being four in number with two of the cavities opening at sides of the block and at one face thereof and with the other two of said cavities opening at sides of the block and at the opposite face of the latter, a pair of plates secured to said block in substantial coextensive contact with said one and said opposite face thereof, respectively, and thereby cooperating with said cavities to define substantially closed spaces containing said fixed contact strips.
 5. The switch according to claim 4 further defined by, each of said fixed contacts being in the form of a spring strip having an end adjacent the portion of the associated cavity which opens at a side of the block, and end of each strip being bent to define a push-in terminal.
 6. The switch according to claim 4 further defined by, said plates each having an opening in coaxial relation with the opening in the other plate, which openings respectively receive opposite end portions of said cylinder thereby rotatably mounting the latter.
 7. The switch according to claim 2 further defined by, said cylinder having a cutout portion adjacent one end thereof receiving said first movable contact with opposite ends of the latter disposed adjacent the outer surface of the cylinder, said cylinder having another cutout portion at its other end receiving said second movable contact with opposite ends of the latter disposed adjacent the outer surface of the cylinder.
 8. The switch according to claim 7 wherein said first movable contact is identical with said second movable contact, and wherein the contacts defining each of said first and second pairs of fixed contacts are identical with each other.
 9. The switch according to claim 1 in combination with a trigger actuated switch, the latter being of the type adapted for mouNting in a portable tool and including a body movably mounting a trigger, said base being fixedly mounted on said body, a manual actuating arm connected with said member for rotating the same back and forth between its first and second positions.
 10. The combination according to claim 9 further defined by, said arm being pivotally mounted on said base intermediate the ends of the former, one end of the arm being engaged with said member and the other end of the arm being disposed in the vicinity of said trigger.
 11. A switch comprising: a. base means mounting first and second pairs of fixed contacts, which base means define a bore interiorly thereof, which bore exposes portions of each of said fixed contacts; b. a member received in said bore for rotation about the longitudinal central axis thereof; c. said member having integral coaxial formations journaled by said base means thereby supporting said member for rotation about said axis, said member having another integral formation eccentric with respect to said axis; d. said base means having an opening receiving said another formation and permitting movement thereof in said opening during corresponding movement of said member back and forth between first and second positions; e. a portion of said another formation extending through said opening and being disposed exteriorly of said base means; f. an actuating arm pivotally mounted by said base means, which arm has a recess receiving said another formation whereby actuation of said arm serves to move said member back and forth between said positions thereof; and g. a third pair of contacts mounted by said member for operative engagement with said first and second pairs of fixed contacts for establishing a current path when said member is in said first position and for establishing a different current path when said member is in said second position.
 12. The switch according to claim 11 further defined by said member having a pair of cutout formations receiving said third pair of contacts, respectively, said third contacts being in the form of strips contained in planes parallel with said axis of rotation.
 13. The switch according to claim 11 further defined by said base means having a plurality of cavities each opening into said bore and respectively receiving portions of said fixed contacts, said portions of said fixed contacts being shaped to define push-in terminals.
 14. A switch comprising: a. base means including block means defining a central bore, a first pair of cavities adjacent one end of the bore and communicating therewith and a second pair of cavities adjacent the other end of the bore and communicating therewith; b. a member mounted for rotation about the longitudinal central axis of said bore; c. first and second pairs of contact strips mounted respectively in said first and second pairs of cavities by engagement with walls of the latter, with a portion of each of said strips extending into said bore and thereby defining a contact making surface extending longitudinally of the bore; d. said base means including plate means covering said first and second pairs of cavities thereby capturing and substantially enclosing said first and second pairs of contact strips therein; e. a third pair of contact strips carried by said member and each having a pair of contact making surfaces extending longitudinally of said bore adjacent the outer surface of said member, said surfaces of the third pair of contact strips being arranged for operative engagement with said contact making surfaces of said first and second pairs of contact strips for establishing a current path when said member is in said first position and for establishing a different current path when said member is in another position; and f. the contact making surfaces of two of said contact strips extending longitudinally of said bore to an extent such that electrical communication is established between one contact strip of said first pair of contact strips and one contact strip of said second pair of contact strips simultaneously with establishment of electrical communication between the other contact strip of said first pair of contact strips and the other contact strip of the second pair of contact strips when said member occupies one of its aforesaid positions for establishing one of said current paths. 